battery drain rate question

[Kuro]

Anyone know the typical drainage rate of a motorcycle battery?

A typical one such as a Yuasa YTX9-BS.

I get ~12.73V after a full charge (let sit for 30 mins to stabilize) and the next morning (roughly 8hours later) its at 12.63V.

I'm trying to diagnose a battery charging problem (bike dies while riding, battery out of juice) and I'm trying to rule out a bad battery. I know a battery is supposed to discharge slowly... just dont know how fast.

Any input appreciated. Thanks.

 

[DJM]

12.6 is fully charged. The 12.73 is surface charge on the battery plates and dissipates after 6 hours or so. Start the bike and measure the battery voltage at idle and then increase the rpm to 3000 and see if the voltage changes. Should be approx. 13.7 to 14.2 volts.

 

[silverbullet132]

www.electrosport.com/media/pdf/fault-finding-diagram.pdf

Hope that helps

 

[frekeyguy]

What's the voltage across the terminals at idle - 3k And 5k rpm?

 

[Kuro]

thanks for the replies
wow that link is crazy useful ... definitely saving that pdf into my library of useful notes
I'll check the voltage while running. First thing I pulled was the rectifier and its not faulty, although one of the terminals is slightly corroded. Maybe bad connection? Anyway, I'll report back if problem isnt solved. (or if it is solved too)

 

[frekeyguy]

thanks for the replies
wow that link is crazy useful ... definitely saving that pdf into my library of useful notes
I'll check the voltage while running. First thing I pulled was the rectifier and its not faulty, although one of the terminals is slightly corroded. Maybe bad connection? Anyway, I'll report back if problem isnt solved. (or if it is solved too)

How did you determine that your rectifier was not faulty?

What is this a 03/04 636?

 

[Kuro]

This is from a 2003 R6. Not my Kawi. I think the 03 Yamaha R6 is known for bad r/r's ...

I tested each terminal to ensure theres a voltage drop between certain terminals.

Theres the top two terminals and I tested between a top terminal and any one of the bottom 3 terminals.
I did notice a bit of corrosion on the bottom left terminal so that may be an issue.

flipped the polarity to see if current would run in the opposite direction to make sure diode is working the way it should and sure enough, its working the way it should.

 

[frekeyguy]

This is from a 2003 R6. Not my Kawi. I think the 03 Yamaha R6 is known for bad r/r's ...

I tested each terminal to ensure theres a voltage drop between certain terminals.

Theres the top two terminals and I tested between a top terminal and any one of the bottom 3 terminals.
I did notice a bit of corrosion on the bottom left terminal so that may be an issue.



flipped the polarity to see if current would run in the opposite direction to make sure diode is working the way it should and sure enough, its working the way it should.

you have a voltage tester....test the voltage at those RPM ranges and report back....very simple test to do to see what kind of input voltage you have.

 

[skapan]

I've always been told that the typical discharge rate sitting on the shelf is 1% per day.
As you're checking the reg/rec you should also check the female terminals in the connector. If there's any evidence of heat (discolouration, plastic warped or deformed) they may not make a tight enough connection, and will get hot and fail when the alternator is working. Happened to me on a Suzuki, never had to replace the reg/rec just kept fixing the harness.

 

[Kuro]

The previous owner told me there was a charging "problem" .... but based on these findings, I'm doubting if there is even a charging problem at all. Apparently, the bike would just die while riding (sputtering while dying) and the battery would be completely drained.

Battery sat for about a week untouched, checked battery voltage before use, 12.55V.
Checked battery voltage at 5000 rpm, 14.2V.